School appliance.



E. O. JACOBS,

SCHOOL APPLIANCE.

APPLIOATION FILED JULY 20, 1912.

Patented Mar. 16, 1915.

EDWIN C. JACOBS, F NOR/WALK, OHIO.

SCHOOL APPLIANCE.

Application filed July 20, 1912.

To all whom it may concern .Be it known that I, EDWIN C. James, acitizen of the United States, and a resident of Norwalk, in the countyof Huron and State of Ohio, have invented certain new and usefulImprovements in School Appliances, of which I hereby declare thefollowing to be afull, clear, and exact description,

such as will enable others skilled in the art to which it appertains tomake and use the same,

The objects of the invention are to provide a combined protractor andchart for educational and other uses, mainly designed to facilitate theinstruction of children in the use of fractions by the division andsubdivision of reat arcs into fractional parts, thus providing an easymethod of teaching fractions, and it also has reference to a simple andeasy method of drawing divisions of the earths surface, such asparallels of latitude and great arcs or meridians and thus make easy thedrawing of parts which are usually a difiicult matter for young childrento draw. To accomplish these objects triangles representing divisions ofthe earths surface are cut from a disk representing a segment of theglobe, and also a ruler B pivoted at the center of said disk is providedwith straight and curved edges corresponding to outlines of bothtropics, the equator, and some of the meridians, and is also providedwith centers from which the remaining meridians can readily be struck,using the center of the disk mostly as a pivot point, but for theoutside meridians difi'erent centers are marked on the equator of thedisk to form true meridians. 3

Other features of utility of the device appear also in the followingdescription and are illustrated in the accompanying drawings, andspecifically pointed out in the claims.

In the accompanying drawings Figure 1 is a plan view of the completedevice; Fig. 2 is a detail view of the ruler by means of which thelines, which are the most difficult of execution can be drawn upon themap; Figs. 3 and 4 illustrate separately formed sectors.

In Fig. 1, 1 is a disk which may be of card board celluloid, or otherthin rigid material. The upper portion'upon which a great circle 0 isdrawn is graduated in degrees and fractions thereof and triangles 2, 3,4, 5, 6, and

Specification of Letters Patent.

vmore can be drawn.

Patented Mar. 16, 1915.

Serial No. 710,627.

7 or a greater or less number of them as desired are cut out of thedisk, and the balance of the fractional units are marked by notches fromwhich to draw extra radii. These sectors represent respectively 2;, e

and other fractional parts of the'whole disk and by using the radialedges E, E, of the sectors as rulers, the sectors can be easily copiedby children upon paper placed below the disk, also stars having anydesired numbers of points can be made or other figures having definiteangles. Of these a large variety can be made using the center A of thedisk as a center for each figure.

The graduations on the edge of the disk can be made as fine as desired.At 8 and 9 having one straight edge 10 and curved edges 11, 12 and 13.The curved edge 11 is used to draw the lines of the tropics and toaccomplish this the ruler is placed in the horizontal position and a pinor needle is thrust through the opening A in the ruler and A in thechart and the edge 11 will then coincide with the dotted line L in theFig. l and one half of the tropic line can be drawn. The ruler is thenturned over and the other half is drawn. This position of the ruler isshown in Fig. 1 in dotted lines. To draw the meridians the ruler R- isplaced in the vertical position with a pointed extremity R at the NorthPole and two meridians can be drawn by means of the curved edges 12 and13, and by turning over the ruler two or The southern half of the samemeridian can be drawn by placing the pointed extremity at the SouthPole. By using the opening A, A, in the ruler as a center and placingthe pivot pin in the opening A in the chart and the pencil at A, A, A inthe ruler the meridians, M, M can be drawn and by placing the pivot pinin the openings B, B in the ruler and A in the chart and the pencil at Bin the ruler the meridians M M can be drawn.

The parts of the chart can be used as an integral disk and inseparable,or the triangular portion "1 and the zones 2, 2', can be separate andjoined to the rest of the disk by any means such as the staples S,-S...

In Fig. 2 the ruler R is shown provided with a slot 0, the sides ofwhich are provided with means for locating the position of the pencil indrawing circles, comprising preferably notches 0, o, positioned atpredetermined distances apart in which the point of a pencil can beplaced when it is desired to draw circles or arcs of differentdiameters. The ivotal ruler R can also be used in adrawmg radiibytracing along its straight li d 6 0- v aving described the inventionwhat I claim as new and desire to'secure by'Letters Patent is:

1. In a drawing instrumenftfor school use,

a charthavinga great circle thereon, and

having its edge graduated in degrees and fractions thereof, and providedwith'open- ,ings having radial edges and also with openings the edges ofwhich represent parallels of latitude.

2. In a drawing instrument, a disk shaped chart, having a great circleinscribed there- ;on, and having its edge graduated in divisions of agreat circle, and a ruler pivoted in the center of the said greatcircle, thersaid v M 1 rul'er "having a straight radial'edge, and acurved. edge corresponding to the lines of the tropics and meridianallines respec-' tively.

3. In an instrument for school use, a chart -having an arc'of a greatcircle inscribed the edges of which represent parallels of latitudel p v5. A ruler designed to be applied to a chart representing theworldssurface, said ruler comprising a body having a straight edge andcurved edges by means of which the tropics and meridian lines can bedrawn and having perforations for the difierent centers about which theruler can be rotated for drawing other meridian lines.

In testimony whereof, I hereunto set -'my hand this 10 day of July,1912.

EDWIN C.-JACOBS. I In presence of WM. M. Mormon, G. ,A. HowELLs.

